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A/C raw water pumps

Discussion in 'HVAC' started by Capt Ralph, Sep 19, 2020.

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  1. Capt Ralph

    Capt Ralph Senior Member

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    For years people were asking me about pool pumps to use instead of 56J water pumps. I remained neutral but always leaned to keeping what was in there with minimum changes.

    Well, now it's my turn. My 1/2hp Marathon died yesterday.
    Looking up pump motors, pumps, internal parts, and pool pumps keep popping up.

    Well, they have a built in strainer, fiber reinforced plastic case, plastic, bronze or stainless impellers. Built for out doors use.
    Just do not come down to 1/3 or 1/2hp motors.

    Then, I have 3 A/C pumps on board. 6 A/Cs with another 24Kbtu to come. All combined 1 1/2 HP.

    For the price of these pool pumps, I can install 2, one as backup, and run everything including primer for the R/O systems.
    Just combine all my pump switches and common hoses with existing manifolds and by next weekend can be finished and on a 1/2 hp new bronze pump budget (or close, it is a boat).

    Please be kind with your thoughts. I'm retired now and on a budget myself.

    I'll duck and hide now
  2. Capt J

    Capt J Senior Member

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    The pool pumps just don't last....... I ran one boat that had them.......6-9 months......and done. I don't think they do well with the cycling on and off so many times, all day long.

    For 1/2 hp, you really cannot beat the AC-5 March pumps with the plastic ends and magnetic drive. They just last and last and last.
  3. Oscarvan

    Oscarvan Senior Member

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    The PO left me with a spare pump in the closet. I suspect the one installed will last for a looooong time.
  4. Capt Ralph

    Capt Ralph Senior Member

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    AC-5 is only 0.125 HP.
    You are correct, they do last a long time.

    https://www.marchpump.com/pump/ac-5c-md-magnetic-drive-pump/

    Somewhere in my last boxes from the old shop, I still have an inventory of impellers with magnet core, axles and ceramic thrust washers. As long as the motor did not get dunked with water, they could out live the A/C equipment they are pumping for.

    I do have one on board as an emgcy pump. We have been covered in clouds and will be for another week. Stb A/Cs doing a fine job for now allowing me / us time to come up with a plan.

    Today, autopsy on the dead motor.
    Last edited: Sep 20, 2020
  5. DOCKMASTER

    DOCKMASTER Senior Member

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    I also like the magnetic drive motors. I have them on my A/C, refer raw water cooling coil and feeding my ice machine. They just seem to work well and last aa long time. The only mystery to me is these type pumps don't like to prime unless you open them after the discharge. At least on my boat. We put in priming Tee's on all ours. After a haul out or winterization, a simple remove the cap, turn the valve and they prime and run great.

    I have the typical pool pump style as you call them as my primary freshwater system mounted atop the pressure tank. I have had two fail in the past 8 years. And I'm not buying cheap pumps. I also have similar pool type pump for my water system on my vacation place that does not have city water. These pumps are always a failure point. They fail to the point that I reconfigured the plumbing to make swap out simple and I keep a spare on hand ready to go. I changed to a slightly different style Bur-Cam pump two years ago and so far it is holding up well.

    Those pool style pumps only seem cheaper upfront. Once you buy several and have the frustration of failure at the most inopportune time you won't have saved anything.
  6. MYTraveler

    MYTraveler Member

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    Regarding the longevity of pool pumps, my experience is pretty good. I started with two 12-volt pumps (one a backup available at the flip of a couple valves) that supply my main bait tank with a pair of jacuzzi 2-speed jacuzzi pumps, the second of which was also a spare and also plumbed to be available at the flip of some valves. The original 12 volt pumps had a very short life expectancy, and once both pumps failed during the same trip (not having a functioning bait tank pump can ruin a trip), which prompted me to try the jacuzzi pumps. Well, that was at least 6 years ago, and I have never had a problem with either. They are in a dry environment, which probably helps alot. The one thing I worry about is the possibility that the plastic parts could fail. I do keep the thru-hulls closed when the pumps are not in use, which may not be practical with AC units.
  7. Pascal

    Pascal Senior Member

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    The March pumps are really good. The most typical failure is the hard plastic impeller breaking up but it s a real easy fix as you can pop the cover and replace it without having to disconnect the hose. Unfortunately they don’t make them big enough for larger systems.
  8. Pascal

    Pascal Senior Member

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    priming issues are almost always because you have a high point between the TH / Strainer and the pump inlet like going over a stronger.
  9. Capt J

    Capt J Senior Member

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    They do make bigger ones now with the similar plastic end. Look on their website at the series 6 and series 7. I've seen them go 10 years or so.........
  10. Capt Ralph

    Capt Ralph Senior Member

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    From the sea cock, the strainer and hose to the pump has to be up hill, no dips for air to get trapped. The pump outlet pointing up. The pump mounted just under the water line.
    No priming issues like this.
    Sadly, in the real world, can not always happen due to lots of issues, engines and bulkheads do get in the way.

    There are self primers, but at 2 to 3 times the cost and size.
  11. Capt Ralph

    Capt Ralph Senior Member

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    Looks like the start contact had arc'd and stuck together.
    Motor could not go into normal run mode when the RPM came up.
    If I can find a new contact board, I may be off and running.

    20200920_141429a.jpg 20200920_141434a.jpg

    Franklin Electric, Mod 1103007489
  12. PacBlue

    PacBlue Senior Member

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  13. vacser

    vacser New Member

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  14. Capt Ralph

    Capt Ralph Senior Member

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    On to other projects.
    Depco pump will be open tomorrow.
    Emails will be waiting for my sales rep.
  15. Capt Ralph

    Capt Ralph Senior Member

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    Sadly, My rep at Depco has past on.
    George Cornelius was a High school rival and a friend at Depco Pump Company.
    He lost to cancer in August.

    Jim Dearden is the next lead for marine sales.

    ,Ralph
  16. Capt Ralph

    Capt Ralph Senior Member

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    Found some hooch and Frankenstein'd a bit last night. Old pump motor starter contacts renewed and working fine tonight.

    A friend of a friend put a pool pump in his large Hatteras a few years ago. I need to follow up on this idea a bit more.
    Not in a hurry now, so the research may take a lil longer.

    crc
  17. justold

    justold Member

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    If you can't find that board you could use an auto start relay . The type used on refrigerator compressors .
  18. Capt Ralph

    Capt Ralph Senior Member

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    Good idea, think I have a few in the shop.
    Just need a contact closed for a few seconds when power is applied, like the start lead on a compressor.

    100104~3.GIF